A wide variety of devices are commercially available that prevent the rotation of a nut with respect to a threaded shaft on which it is installed. Some devices, such as the common helical split lock washer, require that the nut be drawn up tightly in order to obtain a locking grip. Other devices, such as prevailing torque lock nuts, exert a constant resistance torque against rotation. This constant resistance to rotation can be an annoyance during the assembly of products, as it takes time and effort both to install and to remove prevailing torque lock nuts over long threaded shafts; also these nuts can usually be reused for only a few times before the initial prevailing torque starts diminishing due to the wearing away of rubbing surfaces. Washers having internal tangs that fit into shafts with axial keyways are sometimes used; after a nut is drawn up tightly against the washer an edge of the washer is simply bent back over a flat of the nut to prevent nut rotation. Nuts having radially slotted faces (castellated nuts) are commonly used with cotter pins which are inserted through the nut slots and radial holes through the shaft to positively prevent rotation. Both tanged washers and cotter pins are usually discarded after a single use; they are time consuming to install and remove, and used cotter pins laying around loose present a hazard to both personnel and machinery.
Hence there is a need for a simple, inexpensive, and reusable position locking device that will allow a nut to be freely installed over a long length of threaded shaft, yet will allow it to be locked in a desired position and then later unlocked and freely removed.